class_name FarmViewportController
extends RefCounted

# 农场视口控制器：
# - 只缩放土地、背景、房屋、宠物等农场内容，不影响顶部资源栏和弹窗。
# - 单指/鼠标拖动用于预览农场地图，范围限制在 2000x2000。
# - 双指缩放用于移动端；Ctrl + 鼠标滚轮是桌面调试入口。
const ZOOM_STEP := 0.05
const MAP_PREVIEW_SIZE := Vector2(2000.0, 2000.0)
const PAN_DRAG_THRESHOLD := 8.0

var _owner: Control
var _panel_size := Vector2(640.0, 960.0)
var _zoom_min := 1.0 / 1.5
var _zoom_max := 1.3
var _scene_root: Control
var _zoom_backdrop: TextureRect
var _zoom := 1.0
var _scene_offset := Vector2.ZERO
var _active_touches: Dictionary = {}
var _pinch_start_distance := 0.0
var _pinch_start_zoom := 1.0
var _pan_started_callback: Callable
var _pan_finished_callback: Callable
var _touch_pan_start := Vector2.ZERO
var _touch_pan_started := false
var _mouse_pan_active := false
var _mouse_pan_start := Vector2.ZERO
var _mouse_pan_started := false


func setup(owner: Control, panel_size: Vector2, zoom_min: float, zoom_max: float) -> void:
	_owner = owner
	_panel_size = panel_size
	_zoom_min = zoom_min
	_zoom_max = zoom_max
	_setup_scene_root()


func scene_root() -> Control:
	return _scene_root


func zoom_backdrop() -> TextureRect:
	return _zoom_backdrop


func zoom() -> float:
	return _zoom


func scene_offset() -> Vector2:
	return _scene_offset


func map_preview_size() -> Vector2:
	return MAP_PREVIEW_SIZE


func set_pan_started_callback(callback: Callable) -> void:
	_pan_started_callback = callback


func set_pan_finished_callback(callback: Callable) -> void:
	_pan_finished_callback = callback


func handle_input(event: InputEvent) -> bool:
	# ScreenTouch 只记录触点，真正缩放在 ScreenDrag 中根据两点距离比例计算。
	var touch_event := event as InputEventScreenTouch
	if touch_event != null:
		if touch_event.pressed:
			_active_touches[touch_event.index] = touch_event.position
			if _active_touches.size() == 1:
				_touch_pan_start = touch_event.position
				_touch_pan_started = false
		else:
			var was_touch_panning := _touch_pan_started
			_active_touches.erase(touch_event.index)
			_pinch_start_distance = 0.0
			if _active_touches.is_empty():
				_touch_pan_started = false
				if was_touch_panning:
					_notify_scene_pan_finished()
		if _active_touches.size() == 2:
			_begin_pinch_if_needed()
			return true
		return false

	var drag_event := event as InputEventScreenDrag
	if drag_event != null and _active_touches.has(drag_event.index):
		_active_touches[drag_event.index] = drag_event.position
		if _active_touches.size() == 2:
			_update_pinch_zoom()
			return true
		if _active_touches.size() == 1:
			return _handle_touch_pan(drag_event.position, drag_event.relative)

	var mouse_event := event as InputEventMouseButton
	if mouse_event != null and Input.is_key_pressed(KEY_CTRL):
		# Web 预览和桌面调试无法稳定模拟双指时，用 Ctrl + 滚轮验证缩放边界。
		if mouse_event.button_index == MOUSE_BUTTON_WHEEL_UP and mouse_event.pressed:
			set_zoom(_zoom + ZOOM_STEP)
			return true
		if mouse_event.button_index == MOUSE_BUTTON_WHEEL_DOWN and mouse_event.pressed:
			set_zoom(_zoom - ZOOM_STEP)
			return true
	if mouse_event != null and mouse_event.button_index == MOUSE_BUTTON_LEFT:
		if mouse_event.pressed:
			_mouse_pan_active = true
			_mouse_pan_start = mouse_event.position
			_mouse_pan_started = false
		else:
			var was_mouse_panning := _mouse_pan_started
			_mouse_pan_active = false
			_mouse_pan_started = false
			if was_mouse_panning:
				_notify_scene_pan_finished()
		return false

	var motion_event := event as InputEventMouseMotion
	if motion_event != null:
		if _mouse_pan_active and Input.is_mouse_button_pressed(MOUSE_BUTTON_LEFT):
			return _handle_mouse_pan(motion_event.position, motion_event.relative)
		_mouse_pan_active = false
		_mouse_pan_started = false
	return false


func set_zoom(value: float) -> void:
	# 需求要求最大放大 0.3 倍、最大缩小 1.5 倍；上下限由 bootstrap 传入，统一在这里 clamp。
	_zoom = clampf(value, _zoom_min, _zoom_max)
	_apply_zoom()


func _setup_scene_root() -> void:
	if _owner == null or _scene_root != null:
		return
	var ground := _owner.get_node_or_null("Ground") as TextureRect
	_scene_root = Control.new()
	_scene_root.name = "FarmSceneRoot"
	_scene_root.size = MAP_PREVIEW_SIZE
	_scene_root.mouse_filter = Control.MOUSE_FILTER_IGNORE
	_scene_root.pivot_offset = _panel_size * 0.5
	_owner.add_child(_scene_root)
	_owner.move_child(_scene_root, 0)
	if ground != null and ground.texture != null:
		# 使用同一张背景铺到预览范围；素材不够时先允许拉伸，后续按资源补齐。
		_zoom_backdrop = TextureRect.new()
		_zoom_backdrop.name = "FarmZoomBackdrop"
		_zoom_backdrop.position = Vector2.ZERO
		_zoom_backdrop.size = MAP_PREVIEW_SIZE
		_zoom_backdrop.texture = ground.texture
		_zoom_backdrop.stretch_mode = TextureRect.STRETCH_KEEP_ASPECT_COVERED
		_zoom_backdrop.mouse_filter = Control.MOUSE_FILTER_IGNORE
		_scene_root.add_child(_zoom_backdrop)
		for path in ["Ground", "House", "DogHouse", "FenceBack", "GameView", "FenceFront", "PetLayer"]:
			var node := _owner.get_node_or_null(path) as CanvasItem
			if node != null:
				# reparent(true) 保留当前全局变换，迁移到缩放根节点后画面不跳动。
				node.reparent(_scene_root, true)
		_center_land_content_on_map()
		_scene_offset = _default_scene_offset()
		_apply_zoom()


func _handle_touch_pan(position: Vector2, relative: Vector2) -> bool:
	if not _touch_pan_started:
		if _touch_pan_start.distance_to(position) < PAN_DRAG_THRESHOLD:
			return false
		_touch_pan_started = true
		_notify_scene_pan_started()
	_apply_pan(relative)
	return true


func _handle_mouse_pan(position: Vector2, relative: Vector2) -> bool:
	if not _mouse_pan_started:
		if _mouse_pan_start.distance_to(position) < PAN_DRAG_THRESHOLD:
			return false
		_mouse_pan_started = true
		_notify_scene_pan_started()
	_apply_pan(relative)
	return true


func _apply_pan(delta: Vector2) -> void:
	if _scene_root == null:
		return
	_scene_offset = _clamped_scene_offset(_scene_offset + delta)
	_scene_root.position = _scene_offset


func _notify_scene_pan_started() -> void:
	if _pan_started_callback.is_valid():
		_pan_started_callback.call()


func _notify_scene_pan_finished() -> void:
	if _pan_finished_callback.is_valid():
		_pan_finished_callback.call()


func _begin_pinch_if_needed() -> void:
	if _pinch_start_distance > 0.0:
		return
	var points := _active_touches.values()
	# 记录初始两指距离和当前缩放，后续按距离比例换算目标 zoom。
	_pinch_start_distance = maxf((points[0] as Vector2).distance_to(points[1] as Vector2), 1.0)
	_pinch_start_zoom = _zoom
	_notify_scene_pan_started()


func _update_pinch_zoom() -> void:
	var points := _active_touches.values()
	var distance := maxf((points[0] as Vector2).distance_to(points[1] as Vector2), 1.0)
	if _pinch_start_distance <= 0.0:
		_pinch_start_distance = distance
		_pinch_start_zoom = _zoom
		return
	set_zoom(_pinch_start_zoom * distance / _pinch_start_distance)


func _apply_zoom() -> void:
	if _scene_root == null:
		return
	_scene_root.scale = Vector2(_zoom, _zoom)
	_scene_offset = _clamped_scene_offset(_scene_offset)
	_scene_root.position = _scene_offset
	if _zoom_backdrop != null:
		_zoom_backdrop.visible = true
	var ground := _scene_root.get_node_or_null("Ground") as TextureRect
	if ground != null:
		ground.visible = false


func _clamped_scene_offset(value: Vector2) -> Vector2:
	var scaled_map_size := MAP_PREVIEW_SIZE * _zoom
	var min_offset := _panel_size - scaled_map_size
	return Vector2(
		clampf(value.x, minf(min_offset.x, 0.0), 0.0),
		clampf(value.y, minf(min_offset.y, 0.0), 0.0)
	)


func _default_scene_offset() -> Vector2:
	return _clamped_scene_offset(_panel_size * 0.5 - MAP_PREVIEW_SIZE * 0.5 * _zoom)


func _center_land_content_on_map() -> void:
	if _scene_root == null:
		return
	var land_rect := _land_content_rect()
	if land_rect.size == Vector2.ZERO:
		return
	var delta := MAP_PREVIEW_SIZE * 0.5 - (land_rect.position + land_rect.size * 0.5)
	for path in ["House", "DogHouse", "FenceBack", "GameView", "FenceFront", "PetLayer"]:
		var node := _scene_root.get_node_or_null(path) as Control
		if node != null:
			node.position += delta


func _land_content_rect() -> Rect2:
	var game_view := _scene_root.get_node_or_null("GameView") as Control if _scene_root != null else null
	if game_view == null:
		return Rect2()
	var has_rect := false
	var bounds := Rect2()
	for child in game_view.get_children():
		var control := child as Control
		if control == null:
			continue
		if not _is_land_node_name(String(control.name)):
			continue
		var rect := Rect2(game_view.position + control.position, control.size)
		if not has_rect:
			bounds = rect
			has_rect = true
		else:
			bounds = bounds.merge(rect)
	return bounds if has_rect else Rect2()


func _is_land_node_name(node_name: String) -> bool:
	if not node_name.begins_with("Land"):
		return false
	var suffix := node_name.substr(4)
	return not suffix.is_empty() and suffix.is_valid_int() and int(suffix) >= 0